Benign paroxysmal positional vertigo (BPPV) is the most common cause of positional vertigo and nystagmus. Direction-changing positional nystagmus (DCPN), which refers to the change in the direction of nystagmus with different head positions, is a well-known characteristic of horizontal semicircular canal BPPV. The supine head roll test is commonly used to diagnose horizontal canal BPPV. However, persistent geotropic DCPN observed during this test cannot be explained by conventional mechanisms of canalolithiasis or cupulolithiasis. The concept of a “light cupula” has been proposed to account for this unique nystagmus. In this review, we summarize the historical background, clinical features and diagnostic methods, presumed mechanisms, and treatment approaches of the light cupula phenomenon based on the available literatures up to date.
Objectives Light cupula is characterized by persistent geotropic direction-changing positional nystagmus in a supine head-roll test. The purpose of this study is to investigate if hearing level is influenced by the change of head position in light cupula under the assumption that relative density difference similarly occurs between the tectorial membrane and endolymph.
Methods Twelve patients with unilateral light cupula who underwent positional audiometry were included in this study. Pure tone thresholds were compared among three head positions.
Results Hearing threshold in pure tone audiometry (PTA) of the affected ear was not different from that of the healthy ear. PTA thresholds of the affected side were not significantly different in three head positions; upright seating, cochlear apex-up, and cochlear apex-down positions.
Conclusions Although positional change of nystagmus direction is the most significant clinical feature of light cupula, positional change of hearing level was not observed in those patients. The lack of positional influence on hearing may be explained as follows: (1) the heavier endolymph phenomenon occurs only in the vestibular end organ without involving the cochlea; (2) the light cupula phenomenon is more likely to occur due to light debris mechanism rather than heavier endolymph or lighter cupula mechanism; and (3) the effects of light cupula could be modified by outer hair cells, which work for tuning in the cochlea, even though light tectorial membrane or heavy endolymph occurs.
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Light cupula phenomenon: a systematic review Nilüfer Bal, Melike Altun, Elif Kuru, Meliha Basoz Behmen, Ozge Gedik Toker The Egyptian Journal of Otolaryngology.2022;[Epub] CrossRef
Relapsing polychondritis is a rare multisystemic autoimmune disorder of unknown etiology and characterized by recurrent episodes of inflammation affecting the cartilaginous tissues. Otologic manifestation such as auricular chondritis is one of the most frequent presenting symptoms in relapsing polychondritis, and inner ear symptoms, such as hearing loss, tinnitus, and vertigo, may develop in 7% to 42% of the patients. In this study, we present a 42-year-old male patient with relapsing polychondritis, who experienced two separate episodes of acute vestibular syndrome at the interval of 6 years. At the first vertigo attack, the patient showed left-beating spontaneous nystagmus with sudden hearing loss on the right side, and a bithermal caloric test revealed canal paresis on the right side. At the second vertigo attack, he showed right-beating spontaneous nystagmus, and a bithermal caloric test, compared to that during the first vertigo attack, revealed additional decrease in caloric response on the left side.